Decision-making powers granted by law to a government official must serve the particular purpose of the legislation that is the source of the power.

The person making the decision must take into account those things specifically required by the statute, must not consider anything which the statute identifies as irrelevant to the decision, and may consider those things that the decision-maker can have regard to according to their own reasonable judgment and discretion.

The court will not fetter the decision-maker’s discretion but, once taken, the decision may be tested against reasonableness.

[Engen Petroleum Limited v The Business Zone 1010 CC t/a Emmarentia Convenience Centre]